In recent trials in The Gambia, mass chemoprophylaxis with Maloprim administered over several years by primary health care workers to children aged 3-59 months has reduced both mortality and morbidity without inducing impairment of natural immunity or significant development of drug resistance.

Taking expenditure of both time and money, by both public authorities and village volunteers, into account, the costs and the cost effectiveness of such mass chemoprophylaxis are estimated here.

The cost per child protected per season was (1990 US) $2-84; the cost per childhood death averted was $143.